Problem: Constraints

* H is an integer between 2 and 50 (inclusive).
* W is an integer between 2 and 50 (inclusive).
* s_{i, j} is `.` or `#` (1 \leq i \leq H, 1 \leq j \leq W).
* s_{1, 1} and s_{H, W} are `.`.

Input

Input is given from Standard Input in the following format:


H W
s_{1, 1}s_{1, 2}s_{1, 3} ... s_{1, W}
s_{2, 1}s_{2, 2}s_{2, 3} ... s_{2, W}
:   :
s_{H, 1}s_{H, 2}s_{H, 3} ... s_{H, W}


Output

Print the maximum possible score that Snuke can achieve, or print -1 if the game cannot be completed.

Examples

Input

3 3
..#
#..
...


Output

2


Input

3 3
..#
..
...


Output

2


Input

10 37
.....................................
...#...####...####..###...###...###..
..#.#..#...#.##....#...#.#...#.#...#.
..#.#..#...#.#.....#...#.#...#.#...#.
.#...#.#..##.#.....#...#.#.###.#.###.
.#####.####..#.....#...#..##....##...
.#...#.#...#.#.....#...#.#...#.#...#.
.#...#.#...#.##....#...#.#...#.#...#.
.#...#.####...####..###...###...###..
.....................................


Output

209

Solution (in CPP):

Solution:
#include <bits/stdc++.h>
using namespace std;

int h, w;
vector<string> v;
int d[50][50];
int inf = 1e9+7;
typedef pair<int, int> P;
int dx[4] = {0, 0, -1, 1};
int dy[4] = {1, -1, 0, 0};

int main(){
	cin >> h >> w;
	for(int i=0; i<h; ++i){
		string s;
		cin >> s;
		v.push_back(s);
	}
	for(int i=0; i<h; ++i)
		for(int j=0; j<w; ++j)
			d[i][j] = inf;
	d[0][0] = 0;
	queue<P> q;
	q.push(P(0, 0));
	while(!q.empty()){
		P p = q.front();
		q.pop();
		for(int i=0; i<4; ++i){
			int nx = p.first + dx[i];
			int ny = p.second + dy[i];
			if(0 <= nx && nx < h && 0 <= ny && ny < w && v[nx][ny] == '.' && d[nx][ny] > d[p.first][p.second] + 1){
				d[nx][ny] = d[p.first][p.second] + 1;
				q.push(P(nx, ny));
			}
		}
	}
	int tmp = 0;
	for(int i=0; i<h; ++i)
		for(int j=0; j<w; ++j)
			if(v[i][j] == '#')
				++tmp;
	if(d[h-1][w-1] == inf) cout << -1 << endl;
	else cout << h*w-tmp-d[h-1][w-1]-1 << endl;
}